Connecting elements and spinal column stabilization systems of the type described hereinabove are known from US 2006/0184171 A1 for example. In the case of the known connecting elements, the desired stiffness thereof and especially that of the intermediate section thereof, depends on the prevailing manufacturing tolerances. Furthermore, it is not possible with the known connecting elements for the stiffness of the intermediate section to be specifically set within small ranges during the manufacturing process nor is it possible to adjust it subsequently. Such a “fine adjustment” process would, however, be very advantageous. Moreover, thin-walled springy components are difficult to manufacture whereby in particular, a high surface quality can only be attained with great difficulty using material-removing machining processes. Again, the consequences thereof are unavoidable manufacturing tolerances. Leaf spring elements can of course be easily manufactured by means of wire erosion methods for example, but nevertheless, the structure of the eroded material at the surface may then be changed in a disadvantageous manner. Moreover, residual matter from the eroded wire usually has to be removed by chemical methods such as an etching process for example, this in turn leading to ill-defined dimensions and surfaces. And on top of this, it is not possible for the stiffness of the known connecting elements to be varied, not even intra-operatively should this be required.